Ex situ bioremediation assessment of used engine oil by soil bacteria

The used engine oil (UEO) contains potentially toxic substances that are harmful, to the ecosystem. Its pollution comprises of dangerous Cpds that requires efficient bioremediation techniques This study investigates the construction of local soil bacteria that can remove petrol-UEO (shell 15-40) by metabolic capability and their bioremediation techniques. The 1st objective of this study was achieved by isolating the UEO degraders from polluted soil of mechanical workshops in Selangor, Malaysia that grows well on UEO as a C-source. These isolates were identified as Ochrobacterium intermedium LMG 3301 and Bacillus paramycoides MCCC1A04098 strain. The initial results of GC-MS analysis screening results showed that these microbes act on C9 -C29 in 0.74 (%w/v) UEO-EMSM, with the high TPH% removal by O. intermedium (0-24d). O. intermedium also exhibited increased bacteria numbers than B. paramycoides day 24, showing these microbes can utilize UEO. In the 2nd objective, the RSM optimization and modelling of UEO-HCs biodegradation by O. intermedium LMG 3301, allowed the obtaining of the significant model (P <0.001) with R2 to be 0.9967, and optimal condition (pH7.5, Temperature, 35°C, UEO concentration 5 g/L, and150 rpm), that removed 93% TPH (day 24). The 3rd objective focused on the characterization of Alginate-Attapulgite-Calcium carbonate (AAC) beads, in 20 mL of 1% UEO soil water extract (SWE) for their adsorptive capacities of UEO (in 50-mL capped flasks). The UEO removal efficiency (%RE) of 83 ± 0.32% in SWE associated with the highest number of AAC-beads (No = 20, ∅ = 0.45 cm). The studies of SEM and 2, 3, 5-Triphenyl tetrazolium chlroride (TTC) stain of the AAC immobilized cell (IC) systems, showed that the bacteria grows well in this mixed matrix by indicating that this carrier can be applied in the ICs of UEO-pollution adsorptive bioremedies. The AAC matrix stability (4th objective), and its biocatalytic efficiency to remove UEO in a shake flask (150 rpm/24 days) were verified. On day 24, these ICs exhibited the removal of the nC9 to nC17 with 30% increase in TPH obtained with O. intermedium and the 18% by O. intermedium + B. paramycoides (BC) in UEO, as compared to their counter-free cell systems (FCs). The AAC-ICs of O. intermedium and the BC also removed C9-C29 to 93% and 98%, demonstrating adsorptive-bioremediation capacity of these IC-systems. Additional, studies were conducted in a freeze-dryer with the same microbes. The effects of various cryoprotectants carriers on bacteria were verified during this process to cover up part of the 6th objective. The optimum, survival of 98% was observed in the mixed carrier of 1% starch + 10% skimmed milk with the viability of over 12 weeks at the RT. The 5th objective of this study was the scale up of RSM optimal physical-chemical condition, for free cell (O. intermedium / BC) in 1.5 L of stirred batch reactor (SBR), to study the bioremediation of UEO under elevated aerobic condition (0-5 days). On day five, the BC was more efficient at biodegrading UEO with 10% (85%) TPH increased removal as compared to O. intermedium (77%). In the 6th objective, the bacteria FD-powder and AAC-bead inoculants were tested onto artificial setups of 1.5 kg polluted soil with various UEO concentrations as main Csource; and the urea as partial C-source. The experiments in CRD-FFD3-1 showed that the BC was the most effective. The FD-BC, established fast in the soil enabling the removal of UEO, with 12.05 ± 2.26% to 55.12 ± 4.5% of TPH consumed after 84 days whilst 13.54 ± 0.34% to 33.63 ± 1.8% were attained with AAC-bead bioformulates. The research achieved all objectives of the ex-situ bioremedies of soil and water UEO pollution. It charactizes novel methods and substantial formulated agents (i.e., free cell, adsorptive immobilized cell, and freeze-dried cell) that can efficiently decrease UEO contamination. This study has shown the bio effectiveness of the removal of UEO exsitu exploring two different formulated bacteria isolated from heavily UEO polluted soil of mechanical workshops in Selangor, Malaysia.

Text 121237 (edited).pdf Download (1MB) Official URL or Download Paper: http://ethesis.upm.edu.my/id/eprint/18554

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